1. Field of the Invention
The invention generally relates to a kit for satellite positioning system based guidance of munitions, and in particular, for a kit for conversion of a mortar round to a guided glide bomb.
2. Description of the Related Art
Various unmanned aerial vehicles (UAVs) exist. These UAVs are aircraft that fly without a human crew on board. Examples of UAVs include, for example, the MQ-1 Predator, the MQ-9 Reaper, the RQ-7 Shadow, and others.
One of the advantages of a UAV is that a UAV can loiter in an area for reconnaissance for relatively long periods and is typically difficult to observe. Relatively large UAVs, such as the MQ-1 Predator and the MQ-9 Reaper, can be equipped to carry munitions, such as AGM-114 Hellfire missiles, which can then be fired at a safe distance away from a target. This can save the time it takes to deploy aircraft or the like, and prevent lost opportunities. However, these relatively large UAVs can be expensive to procure and to operate, and typically need airfields from which to operate.
Smaller UAVs, such as the RQ-7 Shadow, are much cheaper than the larger UAVs and are more readily deployable in the field without an airfield. However, these smaller UAVs typically fly at much lower altitudes, at much lower speeds, and have much less load carrying capacity. For example, the RQ-7 Shadow does not have the load carrying capacity to carry large munitions or to carry relatively many munitions unless the munitions are relatively small and light.
Instead, these smaller UAVs can be equipped to drop relatively small gravity bombs when needed. A mortar round is a widely available and relatively lightweight bomb. One example of a conventional kit for guidance of a mortar round is the Roll Controlled Fixed Canard (RCFC) guidance kit by General Dynamics Corp. The RCFC guidance kit appears to be described in U.S. Pat. No. 7,354,017 to Morris, et al., (the '017 patent) which, according to the U.S.P.T.O's assignment records, is assigned to General Dynamics Ordnance and Tactical Systems, Inc. In the '017 patent, FIG. 1 illustrates a projectile control system, FIG. 2 illustrates a mortar round configuration, FIG. 3 illustrates a rocket configuration, FIG. 4 illustrates a projectile, such as a rifled mortar round.
The guidance kit permits the trajectory of a mortar round to vary from a normal ballistic trajectory. For example, the '017 patent describes that “the control section is de-spun to 0 Hz,” and then control surfaces 15 control the trajectory of the projectile. The '017 patent describes that “the control surfaces 15 may be deployable fixed-angle canards, which are initially retracted and are deployed during or after launch of the projectile.” These canards are initially retracted such that the mortar round can still be launched from a mortar tube.
As illustrated in FIG. 2 with the circular arrows, the mortar round configuration is intended for a mortar round that spins after being shot from a mortar tube. However, the configuration is also applicable to being dropped from the air as described in a General Dynamics press release of Dec. 16, 2008, which describes a test in which an 81 mm mortar round was dropped from an aircraft, and a General Dynamics press release of Apr. 1, 2010, which describes the dropping of an 81 mm mortar round from a UAV.
In normal operation, a UAV operates stealthily and goes unnoticed. However, when a conventional mortar round is dropped from a UAV, the UAV becomes relatively easy to spot from the ground as it is flying nearly directly overhead due to the relatively low speed and low altitude operation of these UAVs. The UAV is then vulnerable to being shot down with ground fire, thereby negating the cost advantages of these smaller UAVs. Even when the mortar round is guided via a conventional kit, the UAV must still be flying nearly directly overhead of the target, which is a disadvantage referred to as having almost no standoff range. While a guidance kit attached to a mortar round can steer the mortar round to the target for greater accuracy to compensate for effects such as crosswinds, such conventional guidance kit equipped mortar rounds must still be dropped nearly directly overhead of the target, which renders the dropping UAV vulnerable to ground fire.